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Whats the best way to monitor battery and recharge battery? — Parallax Forums

Whats the best way to monitor battery and recharge battery?

queefy01queefy01 Posts: 1
edited 2004-07-28 12:30 in BASIC Stamp
I am currently working on a project that require both solar power and rechargable battery.· The solar power will supply all the energy needed during day time, and recharge the battery if necessary.· If the solar power is not enough to supply the load, then both solar and battery will provide the energy.· I am just wondering is there any way that I can do this?

Comments

  • steve_bsteve_b Posts: 1,563
    edited 2004-07-28 12:30
    I can't quote IC #'s but I'm pretty sure MAXIM-IC have some "battery management" ICs!

    I've been looking to do somewhat the same (only in a monitoring fashion though--don't want the stamp involved in the charging..YET!).
    There's a N/V article on using an opto isolator as a means to determine battery voltage.· I've just uploaded the actual article.

    I believe it was written for the BS1 as they use the POT fuction....and I believe the replacement function for the BS2 and up is RCTIME.

    I didn't have the proper opto to try this....but they say you can just use an LED and an photosensor contained in their own "DARK" box!

    This should be enough to let you monitor voltages.· As far as WHEN the solar panel is charging?!
    The charger/regulator I have only turns on when the solar voltage is above the battery voltage (there's a certain threshold there...not sure).
    So you'd easily be able to figure out that if you are reading 14volts that odds are the solar panel is charging.·
    But on those overcast days when the regulator could be close to the battery voltage (in a float situation)....how do you know which is active....
    Only thing I can say is put another opto type setup on the solar panel line.· You'll have 2 inputs to read but can then use your program to do some math on the two lines to determine whos providing power!
    Do be aware that solar panels (depending on the size of the one you have) will put out as much as 18volts on a really sunny day and I honestly don't know how low they'll go.· so you should set it up with a range large enough to catch the high end.

    Someone on here might tell you to try an A/D converter (Analog to Digital)...they're neat little devices but only the real $$ ones let you get the range you need.· So you'd need some voltage divider networks (not hard to figure out) to get down to a low enough voltage.· So the A/D method gets to be a bit more to program...depending on the A/D you get!

    Try the opto method in this article first!!· and let me know how you make out....I haven't gotten off my duff yet to do this...but really should!!
    I've got a few of those Light to Frequency converter chips and am thinking of trying one of those (might be better dynamic range!).

    Anyhow....this is the most I've typed in a long time....I'm tired now....good luck! cool.gif

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    Steve
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